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March 2002 Off-Post Quarterly Groundwater Monitoring Report
Section 3 - Groundwater Sampling Procedures
In total, 24 off-post wells were sampled during the March 2002 monitoring event (Figure 1.1). Quarterly off-post groundwater monitoring was performed from March 18 through March 21, 2002. Additional samples were collected in January and February 2002. Off-post wells sampled during this quarterly monitoring event were selected based on previous sampling results and proximity to wells with detectable levels of PCE and TCE and the post boundary. Public and private supply wells located west and south of CSSA were selected for this round of quarterly off-post sampling. Figure 1.1 illustrates the locations of off-post private and public wells sampled during the March 2002 quarterly event.
Wells with detected concentrations above 80 percent of the applicable MCL are sampled on a monthly schedule (the Plan, 2001). Prior to the March 2002 quarterly sampling event, samples were collected from selected wells of concern based on results from the December 2001 monitoring event. Three wells were sampled monthly in January and February (LS-2, LS-3, and OFR-3). Results from these monthly sampling events are presented in Section 4, along with results of the March 2002 quarterly sampling event.
Off-post wells sampled in March 2002 include (see Figure 1.1 for well locations):
| Three public supply wells were sampled in the Fair Oaks area (FO-J1, FO-8, and FO-17). | |
| Three privately owned wells in the Jackson Woods subdivision (JW-9, JW-14, and JW-26). | |
| Three wells in the I-10 area (I10-2, I10-4, and I10-7). | |
| Seven wells in the Leon Springs area: four public wells, LS-1, LS-2, LS-3, and LS-4, and three privately owned wells, LS-5, LS-6, and LS-7. | |
| Three wells in the Ralph Fair Road area (RFR-10, RFR-11, and RFR-12). | |
| One well in the Hidden Springs subdivision, public well HS-2. | |
| Privately owned wells OFR-1, OFR-2 and OFR-3 on Old Fredericksburg Road. | |
| One well (DOM‑2) in the Dominion subdivision, located south of CSSA and suspected source area at AOC-65. |
All wells were sampled from a tap as close to the wellhead as possible, with the exception of I10-7. I10-7 was sampled from a faucet located after the pressurization tank. Arrangements will be made to install a tap before the June 2002 sampling event. Most of the taps were installed by CSSA to obtain a representative sample before pressurization or storage and before it enters the water supply distribution system. Because LS-6, LS-7, RFR-10, and RFR-11 had GAC units installed at the time of the March 2002 sampling, these wells were sampled before and after treatment. Prior to sample collection, water was flushed to engage the well pump. While the well was pumping, the pH, conductivity, and temperature readings were recorded to confirm adequate purging. In accordance with the FSP, the groundwater samples were collected when these parameters stabilized. Field notes, including well purging data are included in Appendix C.
Each groundwater sample collected was analyzed for VOCs using SW846 Method 8260 by APPL Laboratory in Fresno, California. Twenty-four groundwater samples, four post-GAC water samples, two field duplicate samples, two MS/MSD pairs, and four trip blanks were submitted to APPL. The Parsons internal data packages DO5084 #24, #25, #26, and #27 as well as RL83 #62, #63, #64, #65, and #66 contain the analytical results for this sampling event. Laboratory results were reviewed and verified according to the guidelines outlined in the AFCEE QAPP, version 3.0. Data packages were received by Parsons in April 2002, and all packages were submitted to AFCEE on May 3, 2002, where they were placed in line for priority review. These data packages were approved by AFCEE on June 10, 2002.